If you go straight from justin Turner Red Sox on the move shirt just wear your work clothes so you don’t seem fussy. Otherwise, it depends on what you normally wear to work, and the venue. If you wear a suit and tie to work, but the party is at a casual bar or restaurant (a place where on a normal night people would wear jeans) then dress down and wear jeans and a sweater with clean sneakers or leather dress shoes. if you have a casual work place where you wear jeans or a work uniform and the party is at a nicer venue specifically for parties (like a banquet hall) or a nicer bar/restaurant then dress up and wear slacks, a sweater and dress shoes. If you are really really unsure, ask your colleagues what they are wearing. If everyone is unsure wear clean dark black jeans (these could look like dress pants in the dark) a sweater and dress shoes. This outfit would fit in anywhere. In NYC just wear all black and you’ll look chic and appropriate.